39 Replies Latest reply on Feb 5, 2013 1:47 PM by PJayZzzzz

    Uh Oh, Possible Problem with GPU-based Color Management

    Noel Carboni Level 8

      NOTE:  The following could be an unwelcome side effect of installing the ATI 12.11 Beta 4 display driver, which I installed yesterday to try out with my Radeon HD 7850.

       

      Consider this PNG image file - nothing special, sRGB color space, some well-saturated greenish colors...

       

      GreenProblem.png

       

       

      It looks like this to me when opened into Photoshop CS6 with either Normal or Advanced GPU modes enabled:

       

      PhotoshopGreenProblem.jpg

       

       

      Note that the saturated green lamp is completely blacked out.

       

      It looks like this if the GPU Mode is set to Basic:

       

      PhotoshopNoGreenProblem.jpg

       

       

      The data is actually there, and when I sample the colors I find that the Red channel is clipped (zero). 

       

      SamplingBlackOut.jpg

       

       

      That is a clue.  Sure enough, if I raise the black point of the red channel to 1 the problem is averted:

       

      RedChannel1.jpg

       

       

      As it's a pretty obvious glitch I hadn't noticed until just now, this likely started occurring when I installed the new ATI driver yesterday morning, but I'm not sure.  It may be some kind of overflow or underflow in the GPU color-management processing, which is moved to the CPU in Basic mode.

       

      I'm doing more investigation, including ultimately cleaning up and dropping back to the ATI Catalyst 12.8 release, but given this behavior I think I'd advise staying away from the Catalyst 12.11 Beta 4 driver for now.  Assuming this is a driver issue, 12.8 may still be the best in recent Catalyst releases.

       

      I'll follow-up in this thread as I learn more.

       

      -Noel